High doses may cause serious diseases and abnormalities including blood clots, high blood pressure, breast tumours, headaches, tiredness and diarrhoea. It may be harmful to the foetus in pregnancy, and prevent blood clotting in those who are taking warfarin. Vitamin E is a quite dangerous substance, and is only rarely used in medicine.
The recommended daily dietary intake is 3.0 mg. in infants, 6.0 mg. in children and 10 mg. in adults.
A lack of vitamin E (tocopherols) from starvation, poor diet or malabsorption of fats may result in nerve damage. The patient has reduced reflexes, abnormal gait (way of walking), decreased senses of position and vibration, and eye movement abnormalities. A deficiency of vitamin E may also be due to the excessive break down of red blood cells or poor absorption of the vitamin from the gut. Permanent degeneration of the spinal cord is a rare complication.
The diagnosis is confirmed by measuring vitamin E levels in the blood. There is a good response to vitamin E supplements provided there has not been permanent nerve damage.